Computing centers, distribution centers and other locations for electronic components require ventilation systems that provide conditioned supply air and return air for cooling the components therein. Since such air circulating units represent a high risk of fire and smoke gas impact on the highly sensitive components, their separation from the actual location of the components in an independent fire compartment is common practice. In order to prevent the propagation of fire and smoke into other fire compartments, protection devices are used.
Such protection devices are conventionally equipped with fire dampers operated by spring force which during normal operation of the ventilation system are positioned in the longitudinal direction of the supply air and return air flow paths, respectively, and are rotatable about an axis that is transversal to the flow path such that the air-conducting cross-section can be closed in the event of fire. The operation of such a fire damper in normal operation and in the event of fire is schematically shown in FIG. 1 and FIG. 2, respectively.
However, a superior fire separation that corresponds e.g. to a current safety standard according to EN 1047-2 cannot be realized with such protection devices: on the one hand, a minimum thickness of the fire dampers is required. However, the damper thickness is a limiting factor of the ventilation cross-section that is covered in the event of fire as the damper length must be chosen such that a collision with the ventilation duct during the rotation of the fire damper is avoided. Therefore, air tightness cannot be ensured, and due to the remaining leakage flows in the closed position of the fire damper, the fire resistance rating is strongly reduced. On the other hand, the non-covered, heat-conducting metal frame of the ventilation duct also generates an unacceptably high heat transmission between the insulated fire compartments.